Extraction raffinate, definition

To extract a desired component A from a homogeneous liquid solution, one can introduce another liquid phase which is insoluble with the one containing A. In theory, component A is present in low concentrations, and hence, we have a system consisting of two mutually insoluble carrier solutions between which the solute A is distributed. The solution rich in A is referred to as the extract phase, E (usually the solvent layer) the treated solution, lean in A, is called the raffinate, R. In practice, there will be some mutual solubility between the two solvents. Following the definitions provided by Henley and Staffin (1963) (see reference Section C), designating two solvents as B and S, the thermodynamic variables for the system are T, P, x g, x r, Xrr (where P is system pressure, T is temperature, and the a s denote mole fractions).. The concentration of solvent S is not considered to be a variable at any given temperature, T, and pressure, P. As such, we note the following ... 

In order to illustrate an example of process design for the manufacture of enantiopure drug substances on an industrial SMB system, consider manufacturing 10 ton/ year of an enantiopure drug. The racemic drug by definition is a 50 50 mixture of each enantiomer (products A and B). The goal is to process enantiopure drug substances in order to obtain 99 % purity for both the extract and the raffinate. 

The preceding definitions all point out that there are three components involved in liquid-liquid extraction. This is true even if each of these three components is itself a group of multiple components. The concept here is that each group within the multicomponent system plays the role of solute, feed-raffinate, or solvent-extract. The objective is to identify each as a discrete component, even if it is a component mixture, and apply the methodology as given herein. 

No definite reason for these fluctuations could be identified, but it is known that neptunium, due to its complicated redox chemistry, reacts in a very sensitive way to even minor process variations (7,8). Based on these results the proposal was made (J5) to recover the "co-extracted" portion of the neptunium by running the second plutonium and uranium purification cycles under conditions where the Np is directed into the aqueous raffinates (2AW and 2DW streams). In the Pu purification cycle, this can be done by adding sufficient nitrous acid to keep the Np pentavalent, while in the U purification cycle (which is run under slightly reducing conditions) a low acidity and a high loading help to reject Np into the aqueous 2DW stream. The two raffinate streams are combined in WAK in the 3W evaporator, and the Np is thus collected in the concentrate from this unit (3WW stream). Consequently the proposal was made to recover the Np from this 3WW stream by use of the well-known anion exchange process (9,J ). 

Figure 8. Scheme of a four-zone adsorption process, showing the definition of the four zones with respect to the inlet (eluent and feed) and outlet (extract and raffinate) lines and the countercurrent of mobile and stationary phase [153]. 

Classification Petroleum hydrocarbon Definition Complex combination of hydrocarbons obtained as the raffinate from a solvent extraction process consists of predominantly C5-11 aliphatic hydrocarbons Properties B.p. 35-190 C Toxicology OSHA PEL 400 ppm Uses Solvent... 

There exists a definite concentration relationship between the two liquid phases at equilibrium. In Figure 11-2 the feed to the extractor is a solution of organic acid in water, represented by point F. The solvent to the extractor is partially stripped benzene of a composition represented by point S. The feed and solvent form a mixture of the composition represented by point H. If the extractor consists of one equilibrium stage, mixture H will separate into two phases, so that the composition of the extract will be represented by point E and the composition of the raffinate by point R. The composition at point E will be in equilibrium with the concentration at point R. 

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